The 'right hand rule' illustrates the Lorentz force law. This law describes the force exerted on a charged particle moving through a magnetic field. You can use your right hand to illustrate this law of physics as follows:

  1. Extend you right hand as a fist but with the thumb sticking up, (the 'thumbs up hand sign').
  2. Keeping thumb in position, point your index finger out, (like your hand is a pistol).
  3. Keeping the 'cocked pistol' finger position, stick your middle finger out perpendicular to both your thumb and index finger.

Your thumb indicates the direction of motion of the charged particle.

Your index finger indicates the direction of the magnetic field.

Your middle finger indicates the direction of the force on the particle.